A number of commercial processes produce higher value hydrocarbons, particularly high octane number branched alkenes, such as octenes in combination with oxygenated hydrocarbons such as sec-butyl ether, a C.sub.8 -derivative. For example, acid catalyzed hydration reactions of propylene and butenes (1-butene and cis and trans 2-butene) are used to manufacture isopropyl and sec-butyl alcohols, respectively. The sec-butyl alcohol is subsequently oxidized over a catalyst to produce 2-butanone (methyl ethyl ketone). Because of the nature of the reaction system, there are additional reactions which compete with the desired hydration reaction that form alcohols. The primary of these are olefin dimerization and the dehydration of two moles of alcohol to form ethers. In the case of the butene chemistry, dimerization of butenes (C.sub.4 H.sub.8) will form a mixture of octenes (C.sub.8 H.sub.16) in the presence of aqueous sulfuric acid under the reaction conditions employed in sec-butyl alcohol formation. In addition, acid catalyzed dehydration of two moles of sec-butyl alcohol also occurs in the process to form sec-butyl ether. The conversion of sec-butyl alcohol to sec-butyl ether produces C.sub.8 -ethers with boiling points which usually fall within the range of the boiling points of the product octenes. A process which would permit the selective separation and recovery of the hydrocarbons from mixed streams of hydrocarbons and oxygenated hydrocarbons would be a desirable upgrade option.